Overview:

Electromagnetic flowmeter is an induction instrument used to measure the volumetric flow rate of conductive fluids. The HHCD type plug-in electromagnetic flowmeter produced by our company is a new type of fluid flow instrument developed on the basis of pipeline electromagnetic flowmeter. On the basis of retaining the advantages of pipeline electromagnetic flow meters, it addresses the difficulties and high costs of installing pipeline electromagnetic flow meters on large pipelines. Based on the principle of Faraday's law of induction, it uses electromagnetic methods to measure the average velocity of fluids and obtain the volumetric flow rate of fluids. Especially with the use of pressurized opening and installation technology, the plug-in electromagnetic flowmeter can be installed without stopping (water), as well as on cast iron pipes, cement pipes, and PE pipes. The successful development of the plug-in electromagnetic flowmeter provides a new means for detecting fluid flow.

Working Principle:

A sensor is actually a liquid flow velocity measuring instrument. It is a flow velocity measuring instrument made using the principle of Faraday's law of induction. Figure 1 is a schematic diagram of the basic working principle of an insertion type flowmeter. Insert a small electromagnetic flow sensor into a designated position in the measured pipeline using a long rod. When a conductive fluid flows vertically through the working magnetic field of the sensor (when the converter provides excitation current to the sensor, a working magnetic field is generated in the excitation system composed of excitation coils), it is equivalent to the conductor cutting magnetic field lines in the magnetic field. According to Faraday's law of induction, an induced electromotive force is generated at both ends of a conductor. This induced electromotive force is detected by a pair of electrodes in contact with the fluid.

Features:

The sensor has no moving parts inside, simple structure, and reliable operation.

The plug-in electromagnetic structure can be easily installed and disassembled without stopping water under low voltage or pressure conditions. Therefore, it is highly suitable for fluid measurement in existing pipelines and facilitates maintenance and repair of instruments.

The measurement accuracy is not affected by changes in physical parameters such as temperature, pressure, density, viscosity, and conductivity (as long as the conductivity is greater than 20 μ s/cm) of the measured medium.

The sensor has almost no pressure loss and extremely low energy loss.

Adopting advanced low-frequency square wave excitation. Zero point stability, strong anti-interference ability, and reliable operation.

Product details:

Structural classification:

Product Parameters:

Selection of electrodes:

Lining Material List:

Flow range confirmation:

The flow rate of the measured medium in general industrial electromagnetic flow meters should be 2-4m/s. In special cases, the minimum flow rate should not be less than 0.2m/s and the maximum should not be greater than 8m/s. If the medium contains solid particles, the commonly used flow velocity should be less than 3m/s to prevent excessive friction between the lining and the electrode; For viscous fluids, the flow velocity can be chosen to be greater than 2m/s. A higher flow velocity helps to automatically eliminate the effect of viscous substances attached to the electrode, which is beneficial for improving measurement accuracy.

Flow meter:

Selection Notice:

1. The actual maximum working pressure must be less than the rated working pressure of the electromagnetic flowmeter.
2. The minimum and maximum operating temperatures must comply with the temperature requirements specified by the flowmeter. (See parameter table for details)
3. From an economic perspective, it is possible to choose a flow meter with the appropriate diameter corresponding to the flow rate. (See flow range table for details)
4. Select the appropriate accuracy level based on the measurement purpose and function.
5. Select appropriate lining materials based on the corrosiveness, wear resistance, and temperature of the medium.
6. Choose between using an integrated electromagnetic flowmeter or a split type electromagnetic flowmeter based on the requirements and environment of the installation site.

The specific choices are shown in the table below:

Installation requirements:

Selection of installation environment

① Try to stay away from equipment with strong fields, such as large motors, transformers, etc.

② The installation site should not have strong vibrations, and the pipeline should be securely fixed. The ambient temperature should not change significantly.

③ The installation environment should be easy to install and maintain.

Selection of installation location

① The installation position must ensure that the pipeline is always filled with the measured fluid.

② Choose a location with small fluid flow pulses, that is, it should be away from local resistance components such as pumps, valves, elbows, etc.

③ When measuring two-phase (solid, liquid or gas, liquid) fluids, a location that is not prone to phase separation should be selected.

④ Negative pressure should be avoided at the measurement site.

⑤ The diameter or circumference of the side pipeline should be easy to measure, and the ellipticity should be small.

straight pipe length

The length of the straight pipe section on the upstream side of the sensor installation pipeline should be greater than or equal to 10D, and the downstream side should not be less than 5D (D is the diameter of the measured pipeline)

Flow control valves and regulating valves

The flow control valve should be installed on the measured pipeline upstream of the sensor, and the flow control valve should be installed downstream of the sensor. During measurement, the flow control valve should usually be fully open.